Many proposals have been made for tubular enclosures having a longitudinal seam of intermeshing components. In effect, such tubular enclosures are sheets of material wrapped around electrical conductors, tubing, ducts, cables or other elongated objects and closed along the longitudinal seam to provide mechanical protection, electrical shielding, environmental sealing, or the like. Such structures have longitudinal seams having portions shaped to interengage one another. Examples of such designs are disclosed in U.S. Pat. Nos. 2,144,755 to Freedman; 2,739,089 to Hageltorn; 2,782,805 to Leadbetter; 3,099,216 to Jakobsen; 3,106,941 to Plummer; 3,495,306 to Eichberg; 3,517,702 to Mueller; 3,638,286 to Eichberg; French Patent No. and Belgian Patent No. 561,916, however, each of these disclosures is subject to disadvantages and shortcomings avoided by the present invention.
For example, no one of these prior disclosures proposes a one-piece tubular construction formed by extrusion of homogeneous material and having a sufficiently high hardness or stiffness to be placed in hoop tension by reason of the extruded material per se. Such prior jackets may be in tension because of contents of the jacket rather than the jacket itself.
Moreover, and of particular importance, all of these disclosures utilize seam strips formed with portions of different thicknesses to facilitate flexing of the thin areas during engagement and disengagement of the seams. For example, in the earlier Eichberg patent a multiplicity of interengaging hooks are provided interconnected by relatively thin grooves which permit the hooks to flex, whereas in the later issued Eichberg patent the lip edges of the hooks are relatively thin and are of material compounded to flex readily during engagement and separation of the seam parts. The same is true of the Freedman and French patents. The Belgian design proposes relatively thick lips on the hooks relative to the much thinner and more flexible mid-section of the hooks.
The Plummer patent describes a technique for producing a tubular enclosure consisting of multiple parts which require assembly. The patent addresses a problem of integrity of additional seams which may be inherent in such construction.
The Leadbetter patent describes a tubular enclosure which is a single piece but it is not uniform. The thickness of the piece varies laterally. Thin spots are made to facilitate bending in the piece which is made flat.
There are similar disadvantages in the Hageltorn and Mueller patents. These patents also teach that the enclosure should be made flat. This creates the dilemma of either making thin spots that are more flexible or making the entire body out of a more flexible and thus less strong material.
The Jakobsen patent describes a jacket for holding explosives within a tube while holding the tube in place within a tunnel being blasted. This patent describes the use of thin materials with good spring characteristics, but obviously is completely unconcerned with durability or life span of the device.
In effect, the prior tubular jackets are made of relatively soft material which is sufficiently flexible to be made flat and then wrapped around objects to be protected. The seam members are appropriate for such materials.
A need has developed for providing good mechanical protection with a removable jacket which can be installed around conduits, wiring or the like. For example, in a variety of automotive applications fuel lines or electrical wires pass in close proximity or through structural components where abrasion may be of concern. In some of these locations it is desirable to install a semi-rigid jacket around a fuel line, for example, which can provide mechanical support for the fuel line as well as preventing crimping or buckling of the fuel line as well as provide enhanced abrasion resistance. Previous jackets made with soft vinyl, for example, are not suitable.